Estimating effective permeabilities

Abstract

A method for determining effective permeabilities of earth formations. The method includes receiving a database having one or more measurements made on a collection of fluid filled rocks and dividing the measurements into input measurements and output measurements. The input measurements include one or more measured properties of the fluid filled rocks and the output measurements include the corresponding effective permeabilities of the fluid filled rocks. The method then includes constructing a mapping function using the input measurements and the output measurements. The mapping function may then be used to predict the effective permeabilities of one or more rocks that are not part of the collection of fluid filled rocks. As such, the method may then include receiving one or more input measurements made on one or more rocks that are not part of the collection of fluid filled rocks and predicting the effective permeabilities of the rocks using the mapping function and the input measurements made on the rocks.

1 . A method for determining effective permeabilities of earth formations, comprising:
 receiving a database having one or more measurements made on a collection of fluid filled rocks;   dividing the measurements into input measurements and output measurements, wherein the input measurements comprise one or more measured properties of the fluid filled rocks and the output measurements comprise effective permeabilities of the fluid filled rocks;   constructing a mapping function using the input measurements and the output measurements;   receiving one or more input measurements made on one or more rocks that are not part of the collection of fluid filled rocks; and   predicting effective permeabilities of the rocks using the mapping function and the input measurements made on the rocks.   
     
     
         2 . The method of  claim 1 , wherein the measurements are obtained from one or more laboratory or well logging measurements. 
     
     
         3 . The method of  claim 1 , wherein the collection of fluid filled rocks comprises sandstones or carbonates. 
     
     
         4 . The method of  claim 1 , wherein the rocks that are not part of the collection of fluid filled rocks comprise sandstones or carbonates. 
     
     
         5 . The method of  claim 1 , wherein the input measurements comprise fluid saturations, porosity, Nuclear Magnetic Resonance (NMR) T2 response, NMR T1 response or combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein the mapping function is constructed using a linear combination of one or more non-linear functions. 
     
     
         7 . The method of  claim 6 , wherein the non-linear functions are radial basis functions. 
     
     
         8 . The method of  claim 1 , wherein the mapping function is constructed using a weighted sum of one or more non-linear functions. 
     
     
         9 . The method of  claim 1 , wherein the mapping function is a multivariate interpolation function that interpolates the input measurements to the output measurements. 
     
     
         10 . The method of  claim 9 , further comprising calibrating one or more coefficients of the multivariate interpolation function such that the interpolation of the input measurements to the output measurements is exact. 
     
     
         11 . The method of  claim 10 , wherein predicting the effective permeability properties of the rocks comprises using the multivariate interpolation function with the coefficients to derive one or more depth logs of the effective permeability of the rocks. 
     
     
         12 . The method of  claim 1 , further comprising predicting one or more flow rates of one or more fluids in the rocks using the predicted effective permeabilities of the rocks. 
     
     
         13 . The method of  claim 1 , further comprising predicting mobilities of fluids in the rocks using the predicted effective permeabilities of the rocks. 
     
     
         14 . The method of  claim 13 , wherein the mobilities are predicted by dividing the predicted effective permeabilities of the rocks by viscosities of the fluids in the rocks. 
     
     
         15 . The method of  claim 13 , further comprising constructing a producibility index of the earth formations surrounding a well using the predicted mobilities. 
     
     
         16 . The method of  claim 13 , further comprising predicting the flow rates of the fluids in the rocks using the predicted mobilities. 
     
     
         17 . The method of  claim 13 , further comprising selecting casing perforation depths in a borehole penetrating the earth formations using the predicted mobilities, thereby optimizing production rates. 
     
     
         18 . The method of  claim 13 , further comprising predicting a portion of a total flow from the earth formations penetrated by a borehole that will be water using the predicted mobilities. 
     
     
         19 . The method of  claim 1 , wherein the predicted effective permeabilities of the rocks are related to hydrocarbons. 
     
     
         20 . The method of  claim 1 , further comprising predicting continuous depth logs of the earth formations penetrated by a borehole based on the predicted effective permeabilities, the flow rates, the predicted mobilities, fractional water flow of the rocks, or combinations thereof. 
     
     
         21 . The method of  claim 1 , further comprising creating one or more reservoir simulation models based on the predicted effective permeabilities or predicted mobilities of the rocks. 
     
     
         22 . The method of  claim 1 , further comprising predicting relative permeabilities of the rocks by determining a ratio between the predicted effective permeabilities and absolute permeabilities.